Oxygen measurement using visible radiation
First Claim
Patent Images
1. Apparatus for use in an instrument that measures the absorption of a sample by passing radiation through the sample, the sample having more than one absorption line including an absorption line at wavelength λ
-
o, said apparatus serving to positively identify the absorption line being measured as the absorption line at wavelength λ
o, said apparatus comprising;
source means including a diode laser responsive to an applied electric current to produce radiation and emitting a part of that radiation in a first direction toward the sample, and emitting another part of that radiation in a second direction;
a first detector positioned to receive radiation that was emitted in the first direction after it has passed through the sample, and generating a first electrical signal related to the intensity of the radiation received by said first detector;
a filter positioned to intercept the radiation emitted in said direction and having a narrow rejection band centered at wavelength λ
o and substantially transmitting radiation of wavelengths outside the narrow rejection bank;
a second detector positioned to receive radiation that has passed through said filter, and generating a second electrical signal related to the intensity of the radiation received by said second detector;
first means connected to said diode laser for scanning the wavelength of the radiation emitted through a wavelength interval in a continuous manner; and
,second means, connected to said first means and to said second detector, and responsive to the second electrical signal generated by said second detector to determine at what instant in the scanning the wavelength of the radiation emitted by said diode laser equals λ
o.
2 Assignments
0 Petitions
Accused Products
Abstract
Apparatus for measuring the absorption of a gaseous sample and particularly suitable for measuring the concentration of gaseous oxygen makes use of a diode laser whose emission wavelength is adjacent to but spaced from the wavelength of a distinct absorption line. The diode drive current is altered to cause the junction temperature of the laser to change, thereby changing the wavelength of the emitted radiation and in effect scanning it through a range of wavelengths that includes the absorption line. The absorption is determined by a ratio technique and therefore is independent of changes in the laser output power level and drifts and changes in other parts of the optical system.
57 Citations
8 Claims
-
1. Apparatus for use in an instrument that measures the absorption of a sample by passing radiation through the sample, the sample having more than one absorption line including an absorption line at wavelength λ
-
o, said apparatus serving to positively identify the absorption line being measured as the absorption line at wavelength λ
o, said apparatus comprising;source means including a diode laser responsive to an applied electric current to produce radiation and emitting a part of that radiation in a first direction toward the sample, and emitting another part of that radiation in a second direction; a first detector positioned to receive radiation that was emitted in the first direction after it has passed through the sample, and generating a first electrical signal related to the intensity of the radiation received by said first detector; a filter positioned to intercept the radiation emitted in said direction and having a narrow rejection band centered at wavelength λ
o and substantially transmitting radiation of wavelengths outside the narrow rejection bank;a second detector positioned to receive radiation that has passed through said filter, and generating a second electrical signal related to the intensity of the radiation received by said second detector; first means connected to said diode laser for scanning the wavelength of the radiation emitted through a wavelength interval in a continuous manner; and
,second means, connected to said first means and to said second detector, and responsive to the second electrical signal generated by said second detector to determine at what instant in the scanning the wavelength of the radiation emitted by said diode laser equals λ
o. - View Dependent Claims (2, 3)
-
o, said apparatus serving to positively identify the absorption line being measured as the absorption line at wavelength λ
-
4. Apparatus for use in an instrument that measures the absorption of a sample by passing radiation through the sample, the sample having more than one absorption line including an aboorption line at wavelength λ
-
o, said apparatus serving to positively identify the absorption line being measured as the absorption line at wavelength λ
o, said apparatus comprising;source means including a diode laser responsive to an applied electric current to produce radiation and emitting a part of that radiation in a first direction toward the sample, and emitting another part of that radiation in a second direction; a first detector positioned to receive radiation that was emitted in the first direction after it has passed through the sample, and generating a first electrical signal related to the intensity of the radiation received by said first detector; a filter positioned to intercept the radiation emitted in said second direction and having a narrow pass band centered at wavelength λ
o and substantially opaque to radiation of wavelengths outside the narrow pass band;a second detector positioned to receive radiation that has passed through said filter, and generating a second electrical signal related to the intensity of the radiation received by said second detector; first means connected to said diode laser for scanning the wavelength of the radiation emitted through a wavelength interval in a continuous manner; and second means, connected to said first means and to said second detector, and responsive to the second electrical signal generated by said second detector to determine at what instant in the scanning the wavelength of the radiation emitted by said diode laser equals λ
o. - View Dependent Claims (5, 6)
-
o, said apparatus serving to positively identify the absorption line being measured as the absorption line at wavelength λ
-
7. Apparatus for controlling the wavelength of the radiation emitted by a diode laser that is mounted on a heat sink, to equal a particular wavelength λ
-
c where the wavelength is a known function of the temperature of the junction of the diode laser, and Tc is the temperature corresponding to λ
c said apparatus comprising;a coarse control system for comparing the temperature of the heat sink with Tc and for applying heat to or removing heat from the heat sink as required to cause the temperature of the heat sink to approach Tc ; and
,a fine control system for altering the diode laser current in a systematic way to maximize the transmission of a sample of the radiation through a narrow band pass filter having its pass band centered at the wavelength λ
c.
-
c where the wavelength is a known function of the temperature of the junction of the diode laser, and Tc is the temperature corresponding to λ
-
8. Apparatus for controlling the wavelength of the radiation emitted by a diode laser that is mounted on a heat sink, to equal a particular wavelength λ
-
c where the wavelength is a known function of the temperature of the junction of the diode laser, and Tc is the temperature corresponding to λ
c said apparatus comprising;a coarse control system for comparing the temperature of the heat sink with Tc and for applying heat to or removing heat from the heat sink as required to cause the temperature of the heat sink to approach Tc ; and
,a fine control system for altering the diode laser current in a systematic way to minimize the transmission of a sample of the radiation through a narrow band rejection filter having its rejection band centered at the wavelength λ
c.
-
c where the wavelength is a known function of the temperature of the junction of the diode laser, and Tc is the temperature corresponding to λ
Specification
-
- Resources
Litigation Campaign Assessment
Thank you for your request. You will receive a custom alert email when the Litigation Campaign Assessment is available.
×
-
Current AssigneeDynatech Electro-Optics Corporation
-
Original AssigneeHibshman Corporation (Dynasil Corp. of America)
-
InventorsWong, Jacob Y.
-
Primary Examiner(s)Howell, Janice A.
-
Assistant Examiner(s)Hanig, Richard
-
Application NumberUS06/863,315Time in Patent Office663 DaysField of Search250/343, 250/340, 250/341, 250/339, 250/373, 356/39, 356/40, 356/41, 128/633, 128/634, 372/20, 372/43US Class Current250/343CPC Class CodesG01J 3/4338 Frequency modulated spectro...G01N 2021/052 Tubular type; cavity type; ...G01N 21/39 using tunable lasersH01S 5/0622 Controlling the frequency o...
